At the Battle of Teutoburg Forest (aka Battle of Varus), c. 9 CE, a combined force of Germans annihilated a Roman army consisting of three legions including three squadrons of cavalry and six cohorts.

Total War: Rome 2 occurs to me at a difficult legacy. The first part I have played over 1000 hours easy thanks to the incredibly good mod Roma Surrectum the modernization of the graph, all other areas of the game and extended.